Staten Island District Attorney Daniel DonovanDaniel (Dan) Michael DonovanThe Hill's Morning Report — Exploding immigration controversy vexes Washington Progressive group targets GOP moderates on immigration NY GOP House hopeful: No nude photos MORE’s chief rival for the GOP nomination in the special election to replace former Rep. Michael Grimm (R-N.Y.) took herself out of contention on Monday.

Nicole Malliotakis (R-N.Y.), an assemblywoman representing parts of Brooklyn, told New York 1 she would no longer seek the nomination.

"I think it's very important that we stand united behind the Republican nominee because we don't want to lose this seat,” she said. “We want to make sure we have what we have what is the only conservative voice in Washington from New York City. And so with that, I decided to end the exploration.”

Malliotakis is viewed as a rising star in conservative circles in New York City, and she had said previously she was considering a run. She was viewed as the biggest Republican challenger to Donovan, who has said he intends to seek the party's nomination to replace Grimm.

Republicans in New York City have rapidly coalesced around Donovan, the prosecutor at the center of the investigation into the death of Eric Garner.

Over the weekend the Staten Island Republican Party officially backed him as their candidate. The Conservative Party of New York has told The Hill it would be happy with Donovan’s candidacy, removing the danger of a split that’s wreaked havoc on past Empire State special elections.

Donovan has also received support from national Republicans, like Former New York City Mayor Rudy Giuliani and Rep. Pete King (R-N.Y.).

Despite the controversy over the Garner case, Donovan has a solid reputation in New York City as a district attorney. He’s also very popular in Staten Island, one of the most pro-police districts in the city.

Even New York City Mayor Bill de Blasio (D) has said he has a solid working relationship with Donovan.

“I will support the Democratic nominee,” de Blasio said Monday, according to the New York Observer. “But that being said, in my previous personal work with the district attorney, it’s been respectful and professional for sure.”

Assemblyman Michael Cusick (D-N.Y.) and former Rep. Michael McMahon (D-N.Y.) are the two top Democrats considering a run for the open seat.

The Staten Island district runs conservative. Grimm coasted to reelection there in 2014 despite a 20-count indictment hanging over his head at the time.